U.S. patent application number 13/081078 was filed with the patent office on 2012-10-11 for continuous availability between sites at unlimited distances.
This patent application is currently assigned to INTERNATIONAL BUSINESS MACHINES CORPORATION. Invention is credited to Jaime F. Anaya, Paul M. Cadarette, Michael G. Fitzpatrick, David B. Petersen.
Application Number | 20120259968 13/081078 |
Document ID | / |
Family ID | 46966971 |
Filed Date | 2012-10-11 |
United States Patent
Application |
20120259968 |
Kind Code |
A1 |
Anaya; Jaime F. ; et
al. |
October 11, 2012 |
CONTINUOUS AVAILABILITY BETWEEN SITES AT UNLIMITED DISTANCES
Abstract
A continuous availability system including a controller module
executing on a computer processor, the system is configured to
receive a unit of work and to select a primary site from a
plurality of sites to process the unit of work. Once a site is
selected the system is further configured to select one of one or
more processing systems from the primary site to process the unit
of work. The system is additionally configured to replicate the
unit of work to at least one other site once the unit of work is
completed at the primary site. The system is configured to operate
even when the primary site is separated from each of the plurality
of sites by a distance greater than a metropolitan area network and
the operations occur within a customer acceptability window.
Inventors: |
Anaya; Jaime F.; (San Jose,
CA) ; Cadarette; Paul M.; (Hemet, CA) ;
Fitzpatrick; Michael G.; (Raleigh, NC) ; Petersen;
David B.; (Great Falls, VA) |
Assignee: |
INTERNATIONAL BUSINESS MACHINES
CORPORATION
Armonk
NY
|
Family ID: |
46966971 |
Appl. No.: |
13/081078 |
Filed: |
April 6, 2011 |
Current U.S.
Class: |
709/224 ;
709/223 |
Current CPC
Class: |
G06F 9/505 20130101;
G06F 9/5044 20130101 |
Class at
Publication: |
709/224 ;
709/223 |
International
Class: |
G06F 15/16 20060101
G06F015/16 |
Claims
1. A continuous availability system, comprising: a controller
module that executes on a computer processor, the system configured
to: receive a unit of work; select a primary site of a plurality of
sites to process the unit of work; select one of one or more
processing systems of the primary site to process the unit of work;
and replicate the unit of work to at least one other site
responsive to completing the unit of work successfully; wherein the
primary site is separated from each of the plurality of sites by a
distance greater than a metropolitan area network (MAN) and
operations occur within a customer acceptability window.
2. The system of claim 1, further comprising a workload
distribution module, the workload distribution module configured to
perform selecting of the primary site, the selecting of the primary
site comprising determining which of the plurality of sites is
capable of processing the unit of work based on one or more of:
determining that one or more of the plurality of sites is executing
a processing system that can execute the unit of work; available
processing capacity; available network bandwidth; average
transaction execution speed; a number of pending transactions; and
availability of one of the plurality of sites.
3. The system of claim 1, further comprising a workload
distribution module, the workload distribution module configured to
perform selecting of a processing system from the one or more
processing systems, the selecting of a processing system comprising
determining which of the one or more processing systems is
available based on one or more of: a number of queued transactions,
availability of the system to handle additional transactions; and a
number of threads executing within the one or more processing
systems.
4. The system of claim 1, wherein the MAN is a distance greater
than 20 fiber kilometers.
5. The system of claim 4, wherein the customer acceptability window
is a recovery point objective of less than 3 seconds.
6. The system of claim 1, further comprising a workload monitoring
module, the workload monitoring module configured to monitor the
one or more processing systems.
7. The system of claim 1, further comprising automatically
selecting a new primary site from the plurality of sites, and
switching from the new primary site back to the primary site
responsive to determining that the primary site is unavailable
based on one of: a planned outage of the primary site; an unplanned
outage of the primary site.
8. The system of claim 7, wherein the switching is initiated
automatically.
9. The system of claim 1, further comprising an integrated
replication module, the integrated replication module configured to
replicate the unit of work by executing the unit of work at each of
the plurality of sites and maintaining data consistency between the
plurality of sites.
10. A method for providing continuous availability over long
distances, the method comprising: receiving, on a computer, a unit
of work; selecting, on the computer, a primary site of a plurality
of sites to process the unit of work; selecting, on the computer,
one of one or more processing systems of the primary site to
process the unit of work; and replicating the unit of work to at
least one other site responsive to completing the unit of work
successfully; wherein the primary site is separated from each of
the plurality of sites by a distance greater than a metropolitan
area network (MAN) and operations occur within a customer
acceptability window.
11. The method of claim 10, wherein the selecting of the primary
site comprises determining which of the plurality of sites is
capable of processing the unit of work based on one or more of:
determining that one or more of the plurality of sites is executing
a processing system that can executes the unit of work; available
processing capacity; available network bandwidth; average
transaction execution speed; a number of pending transactions; and
availability of one of the plurality of sites.
12. The method of claim 10, wherein the selecting of a processing
system from the one or more processing systems comprises
determining which of the one or more processing systems is
available based on one or more of: a number of queued transactions,
availability of the system to handle additional transactions; and a
number of threads executing within the one or more processing
systems.
13. The method of claim 10, wherein the MAN is a distance greater
than 20 fiber kilometers.
14. The method of claim 13, wherein the customer acceptability
window is a recovery point objective of less than 3 seconds.
15. The system of claim 10, further comprising automatically
selecting a new primary site from the plurality of sites, and
switching from the new primary site back to the primary site
responsive to determining that the primary site is unavailable
based on one of: a planned outage of the primary site; an unplanned
outage of the primary site.
16. The system of claim 15, wherein the switching is initiated
automatically.
17. The system of claim 10, wherein the replicating is performed by
executing the unit of work at each of the plurality of sites and
maintaining data consistency between the plurality of sites.
18. A computer program product for continuous availability over
long distances, the computer program product comprising: a tangible
storage medium readable by a processing circuit and storing
instructions for execution by the processing circuit for performing
a method comprising: receiving a unit of work; selecting a primary
site of a plurality of sites to process the unit of work; selecting
one of one or more processing systems of the primary site to
process the unit of work; and replicating the unit of work to at
least one other site responsive to completing the unit of work
successfully; wherein the primary site is separated from each of
the plurality of sites by a distance greater than a metropolitan
area network (MAN) and operations occur within a customer
acceptability window.
19. The computer program product of claim 18, wherein the selecting
of the primary site comprises determining which of the plurality of
sites is capable of processing the unit of work based on one or
more of: determining that one or more of the plurality of sites is
executing a processing system that can executes the unit of work;
available processing capacity; available network bandwidth; average
transaction execution speed; a number of pending transactions; and
availability of one of the plurality of sites.
20. The computer program product of claim 18, wherein the selecting
of a processing system from the one or more processing systems
comprises determining which of the one or more processing systems
is available based on one or more of: a number of queued
transactions, availability of the system to handle additional
transactions; and a number of threads executing within the one or
more processing systems.
21. The computer program product of claim 18, wherein the MAN is a
distance greater than 20 fiber kilometers.
22. The computer program product of claim 21, wherein the customer
acceptability window is a recovery point objective of less than 3
seconds.
23. The computer program product of claim 18, the method further
comprising automatically selecting a new primary site from the
plurality of sites, and switching from the new primary site back to
the primary site responsive to determining that the primary site is
unavailable based on one of: a planned outage of the primary site;
an unplanned outage of the primary site.
24. The computer program product of claim 23, wherein the switching
is initiated automatically.
25. The computer program product of claim 18, wherein the
replicating is performed by executing the unit of work at each of
the plurality of sites and maintaining data consistency between the
plurality of sites.
Description
BACKGROUND
[0001] The present invention relates generally to continuous
availability between sites at unlimited distances.
[0002] Existing continuous availability and disaster recovery
solutions are limited by a number of factors. Continuous
availability protects against data loss, but is limited to a
maximum amount of distance between sites. Existing solutions
support a maximum distance that is considered too limited for many
customer environments.
[0003] Disaster recovery solutions provide unlimited distance
between sites with minimal data loss, but require starting systems,
applications, and their supporting infrastructure on the backup
site, which may take several hours.
[0004] Both disaster recovery and continuous availability systems
additionally require modifications to software applications, such
as database servers, and hardware, such as routers and switches, in
order to implement the various disaster recovery and continuous
availability functions, and therefore require additional cost, and
reconfiguration in order to implement.
SUMMARY
[0005] An embodiment includes a continuous availability system. The
continuous availability system includes a controller module
executing on a computer processor, the system configured to receive
a unit of work and select a primary site from a plurality of sites
to process the unit of work. Once a site is selected the system is
further configured to select one of one or more processing systems
from the primary site to process the unit of work. The system is
additionally configured to replicate the unit of work to at least
one other site once the unit of work is completed at the primary
site. The system is configured to operate even when the primary
site is separated from each of the plurality of sites by a distance
greater than a metropolitan area network and the operations occur
within a customer acceptability window.
[0006] Another embodiment is a method of performing continuous
availability over long distances. The method includes receiving a
unit of work and selecting a primary site from a plurality of sites
to process the unit of work. Once a site is selected one of one or
more processing systems from the primary site is selected to
process the unit of work. The method additionally replicates the
unit of work to at least one other site once the unit of work is
completed at the primary site. The method operates effectively even
when the primary site is separated from each of the plurality of
sites by a distance greater than a metropolitan area network and
the operations occur within a customer acceptability window.
[0007] Yet another embodiment is a computer program product for
continuous availability over long distances. The computer program
product includes a tangible storage medium readable by a processing
circuit and storing instructions for execution by the processing
circuit. The instructions perform a method, which includes
receiving a unit of work and selecting a primary site from a
plurality of sites to process the unit of work. Once a site is
selected one of one or more processing systems from the primary
site is selected to process the unit of work. The method
additionally replicates the unit of work to at least one other site
once the unit of work is completed at the primary site. The method
operates effectively even when the primary site is separated from
each of the plurality of sites by a distance greater than a
metropolitan area network and the operations occur within a
customer acceptability window.
[0008] Additional features and advantages are realized through the
techniques of the present embodiment. Other embodiments and aspects
are described herein and are considered a part of the claimed
invention. For a better understanding of the invention with the
advantages and features, refer to the description and to the
drawings.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0009] The subject matter that is regarded as the invention is
particularly pointed out and distinctly claimed in the claims at
the conclusion of the specification. The foregoing and other
features, and advantages of the invention are apparent from the
following detailed description taken in conjunction with the
accompanying drawings in which:
[0010] FIG. 1 illustrates a block diagram of a system for
continuous availability across multiple sites at unlimited
distances in an embodiment;
[0011] FIG. 2 illustrates a block diagram of the various components
in a system for continuous availability across multiple sites at
unlimited distances in accordance with an embodiment;
[0012] FIG. 3 is a block diagram that illustrates a simplified
multi-site, multi-application workload in a long distance
continuous availability system in an embodiment;
[0013] FIG. 4 illustrates a block diagram of an individual site
implementation of the long distance continuous availability system
in an embodiment; and
[0014] FIG. 5 illustrates a process flow for long distance
continuous availability in an embodiment.
DETAILED DESCRIPTION
[0015] An embodiment includes a long distance continuous available
system for providing continuous availability, disaster recovery,
workload distribution and replication of application data across a
plurality of sites at unlimited distances. The long distance
continuous available system includes replication modules, which
provides unit of work based replication across all of the plurality
of sites. A unit of work is one or more transactions and/or
processes performed as a group to service one or more requests. In
an embodiment the long distance continuous availability system
provides continuous availability, workload distribution, and
replication services for individual sites separated by an unlimited
geographic area with instant fail over, and a nearly instant
recovery point, all without requiring modification to existing user
applications.
[0016] In an embodiment, the long distance continuous availability
system includes a workload distribution module that collects a
plurality of metrics at the software application, middleware,
operating system, network, and hardware level and uses the
collected metrics to provide disaster recovery and fail over
capabilities across the plurality of sites.
[0017] In an embodiment, the long distance continuous availability
system includes a controller, which integrates the various
continuous availability, disaster recovery, replication, and
workload distribution components of the system.
[0018] Existing continuous availability applications are limited
geographically and/or by recovery time. When a workload is spread
across multiple servers in a single location, those servers often
share a single data repository and therefore all data related to
the workload is stored in the same location. When the workload is
split among different data centers, a single data repository is not
always feasible. In these instances, data from the workload is
stored in data repositories at each site, and the data is
synchronized, bit-by-bit, between the databases at each site. The
time that it takes to synchronize the databases is called latency.
As sites are spread further apart geographically, latency increases
because of the time it takes to move the data over a network in
order to synchronize it. Once latency increases beyond a relatively
small amount of time, data between data centers takes increasingly
longer periods of time to achieve synchronization. Therefore,
continuous availability systems provide acceptable workload
performance only over a limited geographic area. This limited
geographic area is generally 10 to 20 fiber kilometers (i.e. over
10 to 20 linear kilometers of a fiber optic network.)
[0019] Disaster recovery systems are designed to switch between a
primary and backup data center in situations where the primary data
center experiences an outage. All transactions are distributed to
the primary data center and the data is replicated bit-by-bit to
the secondary site or sites. Disaster recovery systems are designed
to meet a certain recovery time objective (RTO) and recovery point
objective (RPO). An RTO is the maximum amount of timed needed to
begin normal operations after the primary site experiences an
outage. Because the backup site is configured to receive
replication data from the primary site, when the primary system
goes down, causing the applications to fail over to the backup
site, a number of systems must be restarted at the backup site
before all of the shared services are released. Therefore, the
minimum RTO is the amount of time that is needed to restart the
various services. This may be nearly an hour under ideal
conditions. An RPO is the unit of time up to which the back up site
is current after the primary data center becomes unavailable. As
data is stored at the primary site, it is continuously replicated
to the backup site. When the primary site goes down, any data that
has not been replicated may be lost. The longer it takes to
replicate the data, the longer the minimum RPO.
[0020] Clients require continuous availability and disaster
recovery systems to be separated by longer distances than are
currently supported. In order for continuous availability and
disaster recovery systems to be considered viable at long
distances, the systems must perform between sites separated by
large distances, and also operate within a customer acceptability
window. In an embodiment, the distance between sites includes
distances greater than the area covered within a metro area network
(MAN.) A MAN is a network that consists of a distance measured in
tens of kilometers up to 20 fiber kilometers. Customers require
that their primary and one or more fail over sites be separated by
distances large enough to ensure that a disaster that affects one
site will not affect the others. Although these distances vary
based on regional and environmental conditions, distances larger
than a MAN often separate the sites. In an embodiment, the customer
acceptability window is measured by the length of the RPO. In an
embodiment, the customer acceptably window an RPO of less than 3
seconds of data.
[0021] Turning now to FIG. 1, a system 100 for implementing
continuous availability across multiple sites at unlimited
distances will now be described. In an embodiment, the system
includes one or more workload distribution modules 108 executing
computer instructions for continuous availability across multiple
sites at unlimited distances. The one or more workload distribution
modules 108 may operate in any type of environment that is capable
of executing a software application. One or more workload
distribution modules 108 may include a high-speed computer
processing device, such as a mainframe computer, to manage the
volume of operations governed by an entity for which a continuous
availability across multiple sites at unlimited distances process
is executing. In an embodiment, the one or more workload
distribution modules 108 are part of an enterprise (e.g., a
commercial business) that implements the continuous availability
across multiple sites at unlimited distances.
[0022] In an embodiment, the system depicted in FIG. 1 includes one
or more sites such as site one 102 and site two 104. Each of the
sites includes one or more systems executing one or more
applications for a workload. The one or more applications include
transaction processing applications, database applications, queue
and queue management operations. Each of the sites includes one or
more network hardware devices and/or software for managing and
distributing network traffic among the one or more systems.
[0023] In an embodiment, the system depicted in FIG. 1 additionally
includes a replication module 112. The replication module 112
replicates data between site one 102 and site two 104 and will be
described in more detail below. In an embodiment, the system
depicted in FIG. 1 further includes a controller module 114. The
controller module 114 controls the operation of various components
such as the one or more workload distribution modules 108 as is
described in more detail below.
[0024] The workload distribution modules 108 and the sites (102 and
104) are communicatively coupled via one or more networks 110. The
networks 110 may be any type of known network including, but not
limited to, a wide area network (WAN), a local area network (LAN),
a global network (e.g., Internet), a virtual private network (VPN),
an intranet and a telephone network. The networks 110 may be
implemented using a wireless network or any kind of physical
network implementation known in the art. The sites such as site one
102 and site two 104 may be coupled to the one or more workload
distribution modules 108 through multiple networks (e.g., intranet
and Internet) so that not all of the sites are coupled to the one
or more workload distribution modules 108 through the same
network.
[0025] The one or more workload distribution modules 108 depicted
in the system of FIG. 1 may be implemented using one or more
servers operating in response to a computer program stored in a
storage medium accessible by the server.
[0026] In an embodiment, units of work 106 are distributed to one
or more of the sites through the one or more workload distribution
modules 108. In an embodiment, users of the various systems
executing at the one or more sites initiate the units of work 106.
In an embodiment, the units of work 106 are transmitted from
systems outside of the sites site one 102 and site two 104 and are
processed by applications within one or more of the sites.
[0027] It will be understood that the execution of the continuous
availability across multiple sites at unlimited distances and
methods described in FIG. 1 may be implemented as modules in
hardware, software executing on general-purpose hardware, or a
combination thereof. Although only two sites are depicted in FIG.
1, it will be understood that the number of sites in FIG. 1 is
limited for clarity and that, in an embodiment, any number of sites
may be implemented. In addition, in embodiments, any geographic
distance may separate the sites. Furthermore, although the one or
more workload distribution modules 108 are depicted as existing
outside of the sites, it will be understood that, in an embodiment,
the one or more workload distribution modules 108 may be located in
one or more of the sites directly.
[0028] FIG. 2 illustrates a block diagram of the various components
in a system for continuous availability across multiple sites at
unlimited distances in accordance with an embodiment. A long
distance continuous availability module 200 includes a workload
distribution module 204. In an embodiment, the workload
distribution module 204 collects metrics from each of site one 210
and site two 218. The metrics collected include processor speed,
pending transactions, transaction execution time, system
availability, network bandwidth utilization and availability, and
any other performance-based metrics as is known in the art. In an
embodiment, the workload distribution module 204 uses the metrics
in order to distribute one or more units of work 208 to site one
210 and site two 212. In an embodiment, if the metrics indicate
that one of the sites is overloaded, the workload distribution
module 204 distributes units of work to the other site.
[0029] In an embodiment, the units of work are received at one of
the sites. In an embodiment, site one 210 is a computer system
executing one or more applications 212 for a workload. In an
additional embodiment, site one 210 is a group of servers, such as
a server farm, executing applications using local load balancing,
or other methods of distributing load as is known in the art. In
yet another embodiment, site one 210 includes a plurality of
systems, each system executing one or more applications. In another
embodiment, site one 210 includes a combination of servers and
server farms each executing one or more applications. In an
embodiment, site one 210 includes one or more monitoring modules,
such as site one monitoring module 214. In an embodiment, the site
one monitoring module 214 is communicatively coupled to the
workload distribution module 204, such as through a network, and
transmits metrics from the site one 210 to the workload
distribution module 204. In an embodiment, the site one monitoring
module 214 is executed on a single computer. In another embodiment,
a monitoring module is executed on each of the systems executing at
the site one 210. In yet another embodiment, a plurality of
monitoring modules execute, one on each server, and report metrics
to the workload distribution module 204. The site one monitoring
module 214 is configured to monitor the systems executing at site
one 210. In an embodiment, the site one monitoring module 214 is
configured to monitor the available hardware processing capacity of
the computer processors executing at the site one 210. In an
embodiment, the site one monitoring module 214 is configured to
monitor the available network capacity of the site one 210. In an
embodiment, the site one monitoring module 214 is configured to
monitor the one or more applications 212 executing at the site one
210. In an embodiment, the site one monitoring module 214 monitors
various characteristics of the one or more applications 212 such as
the number of queued transactions, the availability of the one or
more applications 212 to handle additional transactions, the number
of threads executing within each of the one or more applications
212, and any other application specific characteristics as is known
in the art.
[0030] In an embodiment, site two 218 includes one or more
applications 220, a site two monitoring module 222, and a site two
replication module 224, configured identically to the site one 210.
In an additional embodiment, site two 218 includes additional
applications (not shown) that are not replicated or load
balanced.
[0031] In an embodiment, each of the replication modules 216 and
224 are configured to replicate units of work between the sites,
such as site one 210 and site two 218. In an embodiment, the
replication modules 216 and 224 collect units of work at each of
the sites, and coordinate the execution of those units of work on
the other sites. In embodiments, any number of sites can be
configured to provide load balancing and replication of units of
work. In addition, although the controller module 206 is depicted
as a stand-alone module, it will be understood that, in an
embodiment, the controller module 206 may be executed in the long
distance continuous availability module 200, or any of the
sites.
[0032] In an embodiment, a controller module 206 is in
communication with each of the sites, such as site one 210 and site
two 218 and is configured to coordinate transactions and
replication of the units of work between the various sites. In an
embodiment, the controller module 206 is in communication with the
workload distribution module 204, and uses information provided by
each of those modules to coordinate transactions and replication of
the units of work between the various sites. In an embodiment, long
distance continuous availability module 200 includes the controller
module 206.
[0033] The illustration of FIG. 2 is a simplified representation of
the various components of the long distance continuous availability
module 200 for purposes of clarity. It will be understood by those
of ordinary skill in the art, that additional or fewer components
may be used in alternate embodiments. In additional embodiments,
the layout and configuration of the components may differ from
those of FIG. 2 without affecting the functionality of the long
distance continuous availability module 200. In additional
embodiment, the various components may be located in separate
modules. In further embodiments, the functionality of various
components may be incorporated into a single hardware or software
module.
[0034] FIG. 3 is a block diagram that illustrates a simplified
multi-site, multi-application, long distance continuous
availability system in an embodiment. In an embodiment, the sites,
Site A 302, Site B 304 and Site C 306 executes one or more
applications for processing a workload. The applications generate
and/or consume a workload 308. The workload 308 is provided with
continuous availability, and fail over provisions by a long
distance continuous availability module 316. In an embodiment, the
long distance continuous availability module 316 is in
communication with the various sites via a network, such as the one
or more networks 110 of FIG. 1. In an embodiment, the long distance
continuous availability module 316 is configured to detect that a
primary site is down and automatically fails over (i.e. transmits
future workloads) to one of the other sites. In an embodiment fail
over occurs because of an unplanned outage and is based on metrics
received by a workload distribution module from a monitoring
module, such as the site one monitoring module 214 of FIG. 2. In an
embodiment, the fail over occurs because of a planned outage and is
initiated by a script and/or instructions from an operator. In an
embodiment, the long distance continuous availability module 316
fails back to the primary site automatically based on scripts
and/or instructions from an operator. In yet another embodiment,
the long distance continuous availability module 316 fails back to
the primary site automatically when it detects that the primary
site is available. In an embodiment, the long distance continuous
availability module 316 includes a replication module, such as the
replication module 112 of FIG. 1, a workload distribution module
such as the one or more workload distribution modules 108 of FIG.
1, and a controller, such as controller module 114 of FIG. 1.
[0035] FIG. 4 illustrates a block diagram of an individual site
implementation of the long distance continuous availability system
in an embodiment. The elements of FIG. 4 are executed on one or
more sites such as site one 210 of FIG. 2. In an embodiment, long
distance continuous availability module 402 is communicatively
coupled to one or more applications executing at a site. The long
distance continuous availability module 402 coordinates
distribution of units of work to the workload 404. Workload 404
includes an application interface 406. The application interface
406 facilitates communication of units of work to the workload 404.
The application interface 406 is configured to use any application
interfaces such as TCP/IP, message queuing, remote procedure
execution, or any other interface as is known in the art. The
workload 404 additionally includes a transaction and data storage
408. In an embodiment, the transaction and data storage 408 is a
database storage system. In an additional embodiment, the
transaction and data storage 408 is a file based system. In yet
another embodiment, the transaction and data storage 408 is a
transaction-based storage such as a queue. In yet another
embodiment, the transaction and data storage 408 may be any storage
as is known in the art.
[0036] In an embodiment, the workload 404 additionally includes a
workload monitoring module 410. In an embodiment, the workload
monitoring module 410 monitors the system's processing load. In an
embodiment, the workload monitoring module 410 is configured to
determine the transaction processing speed of the application, the
number of threads executing on the application, the number of
transactions queued for processing, and/or any other application
processing related information. In an embodiment, the workload
monitoring module 410 is communicatively coupled to a monitoring
module, such as the site one monitoring module 214 of FIG. 2, which
transmits the application metrics to the workload distribution
module 204.
[0037] In an embodiment, the workload 404 further includes a system
state monitor 412. The system state monitor 412 communicates to the
long distance continuous availability module 402 whether or not the
workload 404 is currently operating within specified tolerances.
When the workload 404 stops operating correctly, the system state
monitor 412 notifies the long distance continuous availability
module 402.
[0038] FIG. 5 illustrates a process flow for long distance
continuous availability in an embodiment. In an embodiment the
process flow of FIG. 5 is executed on the long distance continuous
availability module 200 of FIG. 2. At block 502 statistics and
metrics are collected from the various applications and sites. In
an embodiment, the statistics and metrics are collected
continuously. At block 504 a unit of work is received. A unit of
work is one or more transactions that are connected with one
another. In an embodiment, the unit of work may be a series of
updates and/or inserts in a relational database and the unit of
work is defined by a first transaction, and terminated by a commit
request, which closes the group of transactions and stores them in
a database. In another embodiment, a logical unit of work is a
series of transactions across multiple backend systems, each
dependent on one another.
[0039] At block 506 a workload distribution module, such as
workload distribution module 204 of FIG. 2, uses the metrics
collected at block 502 to determine which of a plurality of sites
will be used to execute the unit of work. In an embodiment, the
site is selected based on whether or not the site is executing an
application that is targeted for executing the unit of work, on the
available processing capacity, the available network bandwidth, the
average transaction execution speed, the number of pending
transactions, the availability of a site, and/or any other factor
as is known in the art. In another embodiment, a site is selected
iteratively in a "round-robin" fashion. In yet another embodiment,
a site is selected randomly from a group of available sites.
[0040] In an embodiment, if one site is unavailable, such as where
a network is made unavailable, a power outage is encountered, or a
hardware failure exists, the site is automatically removed from
consideration until the issues have been corrected.
[0041] At block 508, the unit of work is transmitted to the
selected site. At block 510, a system within the site is selected
to process the work. In an embodiment, a plurality of systems at
each site may be configured to process a unit of work. At block
512, the unit of work is transmitted to the selected system. At
block 514, the unit of work is executed by the selected system at
the selected site, and the transactions in the unit of work are
committed and stored in a database. At block 516, once the
transactions have been executed, the unit of work is replicated to
all of the other sites that support the same application
environment using a replication module such as each of the
replication modules 216 of FIG. 2. In an embodiment, the
replication occurs asynchronously. In an additional embodiment, the
replication occurs synchronously. In an embodiment, the unit of
work is replicated in its entirety to each of the alternate sites.
At block 518 each of the transactions in the unit of work is
executed and committed by a replication module at each of the
alternate sites in a way that maintains data consistency.
[0042] Technical effects and benefits include a mechanism for load
balancing, fail over, and replication across a number of sites
separated by unlimited distances without requiring application
configuration.
[0043] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the invention. As used herein, the singular forms "a", "an" and
"the" are intended to include the plural forms as well, unless the
context clearly indicates otherwise. It will be further understood
that the terms "comprises" and/or "comprising," when used in this
specification, specify the presence of stated features, integers,
steps, operations, elements, and/or components, but do not preclude
the presence or addition of one ore more other features, integers,
steps, operations, element components, and/or groups thereof.
[0044] The corresponding structures, materials, acts, and
equivalents of all means or step plus function elements in the
claims below are intended to include any structure, material, or
act for performing the function in combination with other claimed
elements as specifically claimed. The description of the present
invention has been presented for purposes of illustration and
description, but is not intended to be exhaustive or limited to the
invention in the form disclosed. Many modifications and variations
will be apparent to those of ordinary skill in the art without
departing from the scope and spirit of the invention. The
embodiment was chosen and described in order to best explain the
principles of the invention and the practical application, and to
enable others of ordinary skill in the art to understand the
invention for various embodiments with various modifications as are
suited to the particular use contemplated
[0045] As will be appreciated by one skilled in the art, aspects of
the present invention may be embodied as a system, method or
computer program product. Accordingly, aspects of the present
invention may take the form of an entirely hardware embodiment, an
entirely software embodiment (including firmware, resident
software, micro-code, etc.) or an embodiment combining software and
hardware aspects that may all generally be referred to herein as a
"circuit," "module" or "system." Furthermore, aspects of the
present invention may take the form of a computer program product
embodied in one or more computer readable medium(s) having computer
readable program code embodied thereon.
[0046] Any combination of one or more computer readable medium(s)
may be utilized. The computer readable medium may be a computer
readable signal medium or a computer readable storage medium. A
computer readable storage medium may be, for example, but not
limited to, an electronic, magnetic, optical, electromagnetic,
infrared, or semiconductor system, apparatus, or device, or any
suitable combination of the foregoing. More specific examples (a
non-exhaustive list) of the computer readable storage medium would
include the following: an electrical connection having one or more
wires, a portable computer diskette, a hard disk, a random access
memory (RAM), a read-only memory (ROM), an erasable programmable
read-only memory (EPROM or Flash memory), an optical fiber, a
portable compact disc read-only memory (CD-ROM), an optical storage
device, a magnetic storage device, or any suitable combination of
the foregoing. In the context of this document, a computer readable
storage medium may be any tangible medium that can contain, or
store a program for use by or in connection with an instruction
execution system, apparatus, or device.
[0047] A computer readable signal medium may include a propagated
data signal with computer readable program code embodied therein,
for example, in baseband or as part of a carrier wave. Such a
propagated signal may take any of a variety of forms, including,
but not limited to, electro-magnetic, optical, or any suitable
combination thereof. A computer readable signal medium may be any
computer readable medium that is not a computer readable storage
medium and that can communicate, propagate, or transport a program
for use by or in connection with an instruction execution system,
apparatus, or device.
[0048] Program code embodied on a computer readable medium may be
transmitted using any appropriate medium, including but not limited
to wireless, wire line, optical fiber cable, RF, etc., or any
suitable combination of the foregoing.
[0049] Computer program code for carrying out operations for
aspects of the present invention may be written in any combination
of one or more programming languages, including an object oriented
programming language such as Java, Smalltalk, C++ or the like and
conventional procedural programming languages, such as the "C"
programming language or similar programming languages. The program
code may execute entirely on the user's computer, partly on the
user's computer, as a stand-alone software package, partly on the
user's computer and partly on a remote computer or entirely on the
remote computer or server. In the latter scenario, the remote
computer may be connected to the user's computer through any type
of network, including a local area network (LAN) or a wide area
network (WAN), or the connection may be made to an external
computer (for example, through the Internet using an Internet
Service Provider).
[0050] Aspects of the present invention are described below with
reference to flowchart illustrations and/or block diagrams of
methods, apparatus (systems) and computer program products
according to embodiments of the invention. It will be understood
that each block of the flowchart illustrations and/or block
diagrams, and combinations of blocks in the flowchart illustrations
and/or block diagrams, can be implemented by computer program
instructions. These computer program instructions may be provided
to a processor of a general purpose computer, special purpose
computer, or other programmable data processing apparatus to
produce a machine, such that the instructions, which execute via
the processor of the computer or other programmable data processing
apparatus, create means for implementing the functions/acts
specified in the flowchart and/or block diagram block or
blocks.
[0051] These computer program instructions may also be stored in a
computer readable medium that can direct a computer, other
programmable data processing apparatus, or other devices to
function in a particular manner, such that the instructions stored
in the computer readable medium produce an article of manufacture
including instructions which implement the function/act specified
in the flowchart and/or block diagram block or blocks.
[0052] The computer program instructions may also be loaded onto a
computer, other programmable data processing apparatus, or other
devices to cause a series of operational steps to be performed on
the computer, other programmable apparatus or other devices to
produce a computer implemented process such that the instructions
which execute on the computer or other programmable apparatus
provide processes for implementing the functions/acts specified in
the flowchart and/or block diagram block or blocks.
[0053] The flow diagrams depicted herein are just one example.
There may be many variations to this diagram or the steps (or
operations) described therein without departing from the spirit of
the invention. For instance, the steps may be performed in a
differing order or steps may be added, deleted or modified. All of
these variations are considered a part of the claimed
invention.
[0054] While the preferred embodiment to the invention had been
described, it will be understood that those skilled in the art,
both now and in the future, may make various improvements and
enhancements which fall within the scope of the claims which
follow. These claims should be constructed to maintain the proper
protection for the invention first described.
* * * * *